Systems and methods for determining set pressure and lift of a spring-operated relief valve

ABSTRACT

A spring-operated relief valve can include an adjustable main spring to bias the valve closed and a load cell that is configured to measure a force exerted by the main spring. Measurements from the load cell can be used to determine a set or crack pressure in the spring-operated relief valve, and to monitor operation of the spring-operated relief valve.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional patent applicationNo. 62/979,129, titled “Systems and Methods for Determining Set Pressureand Lift of a Spring-Operated Relief Valve” and filed on Feb. 20, 2020,the entirety of which is incorporated herein by reference.

BACKGROUND

Spring-operated pressure relief valves are used extensively in systemsand vessels where pressure protection is required. For example, in suchsystems, excess pressure can lead to a process upset, instrumentfailure, or equipment failure. Pressure relief valves allow excesspressure to be relieved by allowing pressurized fluid to flow from anauxiliary passage out of the system.

SUMMARY

Some embodiments provide a spring-operated relief valve that includes amain spring, a pressure adjustment screw, and a disc assembly that isbiased towards a valve seat by the main spring. A load cell can beconfigured to measure a force exerted by the main spring on the discassembly, including to determine the crack pressure and the set pressureof the spring-operated relief valve. In one embodiment, the pressureadjustment screw may be threadably engaged with the load cell. Inanother embodiment, the load cell may be disposed between the pressureadjustment screw and an upper spring washer.

Some embodiments provide a method for setting a set or crack pressurefor a spring-operated relief valve. The method can include pressurizinga valve inlet of the spring-operated relief valve and adjusting a biasof a main spring of the spring-operated relief valve. A load on the mainspring can be determined at a select adjustment of the compression ofthe main spring. A valve-opening movement of the spring-operated reliefvalve can be identified based on the determined load.

Some embodiments provide a method for monitoring operation of aspring-operated relief valve. The method can include using a load cellto measure a force applied by a main spring of the spring-operatedrelief valve. A valve lift for the spring-operated relief valve can bedetermined based on the measured force, as may allow determination oftotal relieved capacity during a relief event (e.g., based ondetermination of a valve lift profile over time), or a set pressure ofthe spring-operated relief valve can be monitored.

Some embodiments provide a spring-operated relief valve. Thespring-operated relief valve can include a valve housing, a valve seat,a disc assembly that is configured to seal against the valve seat toclose the spring-operated relief valve, a main spring, and a load cell.The main spring can be arranged to bias the disc assembly towards thevalve seat to define a set pressure of the spring-operated relief valve.The load cell, during operation of the spring-operated relief valve, canbe in a fixed spatial relationship relative to the valve housing and inmechanical communication with the main spring, the load cell can bethereby configured to measure a force exerted by the main spring on thedisc assembly as the disc assembly moves relative to the valve seat.

In some embodiments, a spring-operated relief valve can include aspindle that extends from a disc assembly to guide movement of the discassembly relative to a valve seat. During operation of thespring-operated relief valve, the spindle is movable relative to a loadcell to open and close the spring-operated relief valve relative tofluid flow across the valve seat.

In some embodiments, a spring-operated relief valve can include aspindle that extends through a load cell, to be movable through the loadcell to open and close the spring-operated relief valve relative tofluid flow across a valve seat.

In some embodiments, a spring-operated relief valve can include apressure adjustment member. A load cell can include internal threads andthe pressure adjustment member is threadably received by the internalthreads. The pressure adjustment member can be thereby threadablyadjustable, relative to the load cell and a valve housing, to adjust adegree of compression of a main spring.

In some embodiments, a spring-operated relief valve can include a loadcell. The load cell can be in mechanical communication with a mainspring via a pressure adjustment member to measure a force exerted bythe main spring on a disc assembly.

In some embodiments, a spring-operated relief valve can include a valvehousing that includes a bonnet and a cap. A load cell can be retainedbetween the bonnet and the cap.

In some embodiments, a spring-operated relief valve can include a firstspring washer and a second spring washer. The first spring washer can bedisposed opposite a main spring from a disc assembly. The second springwasher can be disposed opposite the main spring from the first springwasher, between the main spring and the disc assembly. A load cell canbe in mechanical communication with the main spring via the first springwasher.

In some embodiments, a spring-operated relief valve can include a firstspring washer and a second spring washer. The first spring washer can bedisposed opposite a main spring from a disc assembly. The second springwasher can be disposed opposite the main spring from the first springwasher, between the main spring and the disc assembly. A load cell canbe in mechanical communication with the main spring via the secondspring washer.

In some embodiments, a spring-operated relief valve can include a loadcell retained between a first spring washer and a pressure adjustmentmember that is threadably adjustable relative to a valve housing toadjust a degree of compression of the main spring.

In some embodiments, a spring-operated relief valve can include a loadcell integrated with a first spring washer.

In some embodiments, a spring-operated relief valve can include a loadcell. A force measured by the load cell can directly correspond to aforce of fluid on a disc assembly, without reference to a measuredpressure of the fluid.

In some embodiments, a spring-operated relief valve can include a loadcell positioned exterior to a valve housing.

In some embodiments, a spring-operated relief valve can include aspindle that extends from a disc assembly to guide movement of the discassembly relative to a valve seat. A pressure adjustment tube canreceive the spindle and extends between a spring washer and a load cellto transmit force from a main spring to the load cell.

In some embodiments, a spring-operated relief valve can include apressure adjustment member that is threadably adjustable relative to aload cell to adjust, via a pressure adjustment tube, a degree ofcompression of a main spring.

In some embodiments, a spring-operated relief valve can include apressure adjustment member that is adjustable from outside of a valvehousing.

Some embodiments provide a spring-operated relief valve that includes avalve housing, a valve seat, a disc assembly, a spindle, a main spring,and a load cell. The disc assembly can be configured to seal against thevalve seat to close the spring-operated relief valve. The spindle canextend from the disc assembly to guide movement of the disc assemblyrelative to the valve seat. The main spring can be arranged to bias thedisc assembly towards the valve seat to define a set pressure of thespring-operated relief valve. During the operation of thespring-operated relief valve, the load cell can be either immovablysecured within the valve housing or immovably secured outside the valvehousing. The load cell can be in mechanical communication with the mainspring directly or via a rigid intervening component. The load cell canbe thereby configured to measure a force exerted by the main spring onthe disc assembly as the disc assembly and the spindle move relative tothe valve seat and the load cell.

In some embodiments, a spring-operated relief valve can include aspindle and a load cell. During operation of the spring-operated reliefvalve, the spindle can be movable relative to the load cell to open andclose the spring-operated relief valve relative to fluid flow across avalve seat. The load cell may not be in mechanical communication with adisc assembly via the spindle to measure the force exerted by a mainspring.

Some embodiments provide a method of installing or calibrating aspring-operated relief valve. The method can include using a load cellto directly measure a force applied by a main spring of thespring-operated relief valve, the main spring being arranged to bias adisc assembly of the spring-operated relief valve toward a valve seat ofthe spring-operated relief valve to define a set pressure and a crackpressure of the spring-operated relief valve. The method can alsoinclude one or more of: determining a valve lift for the spring-operatedrelief valve based on the measured force, monitoring a current setpressure or crack pressure of the spring-operated relief valve based onthe measured force, or setting a desired set pressure or crack pressureof the spring-operated relief valve by determining a target load on amain spring of the spring-operated relief valve, the target loadcorresponding to the desired set pressure or crack pressure andadjusting a bias of the main spring of the spring-operated relief valveuntil the force measured by the load cell corresponds to the targetload.

In some embodiments, a method of installing or calibrating aspring-operated relief valve can include determining a total relievedcapacity for a relief event based on a plurality of valve lifts that areidentified based on a load cell measuring a plurality of forces appliedby a main spring during the relief event.

In some embodiments, a method of installing or calibrating aspring-operated relief valve can include using a load cell to directlymeasure a force applied by a main spring of the spring-operated reliefvalve. The load cell can be fixedly secured relative to a valve housingof the spring-operated relief valve at one of outside of the valvehousing of the spring-operated relief valve, between a pressureadjustment member and an upper spring washer of the spring-operatedrelief valve, or between a bonnet and a cap of the spring-operatedrelief valve.

In some embodiments, a method of installing or calibrating aspring-operated relief valve can include pressurizing a valve inlet ofthe spring-operated relief valve, adjusting the compression of a mainspring among a plurality of compression loads, using a load cell tomeasure the compression load of the main spring at a select adjustmentof the compression of the main spring, and identifying a valve-openingmovement of the spring-operated relief valve that corresponds to theselect adjustment of the compression of the main spring. Uponidentifying the valve-opening movement, the method can also includedetermining a current set pressure or crack pressure based on themeasured compression load.

Some embodiments provide a method for setting a set pressure or crackpressure for a spring-operated relief valve. The method can includepressurizing a valve inlet of the spring-operated relief valve,adjusting a compression of a main spring of the spring-operated reliefvalve among a plurality of compression loads, using a load cell tomeasure a compression load of the main spring at a select adjustment ofthe compression of the main spring, the load cell being in mechanicalcommunication with the main spring and being spatially fixed relative toa valve body of the spring-operated relief valve during operation of thespring-operated relief valve, and identifying a valve-opening movementof the spring-operated relief valve that corresponds to the selectadjustment of the compression of the main spring. Upon identifying thevalve-opening movement, the method can include determining the setpressure or crack pressure based on the measured compression load.

In some embodiments, a method for setting a set pressure or crackpressure for a spring-operated relief valve can include using a loadcell to measure a compression load of a main spring at a selectadjustment of the compression of the main spring. A pressure adjustmentmember can be used to adjust the compression of the main spring and canbe threadably engaged with the load cell.

In some embodiments, a method for setting a set pressure or crackpressure for a spring-operated relief valve can include using a loadcell to measure a compression load of a main spring at a selectadjustment of the compression of the main spring. The load cell can bedisposed at one of: outside of the valve housing of the spring-operatedrelief valve, between a pressure adjustment member and an upper springwasher of the spring-operated relief valve, or between a bonnet and acap of the spring-operated relief valve.

In some embodiments, a method for setting a set pressure or crackpressure for a spring-operated relief valve can include using a loadcell during operation of the valve to measure a force applied by a mainspring to a disc assembly of the spring-operated relief valve, and oneor more of determining a valve lift for the spring-operated relief valvebased on the measured force or monitoring a current set pressure orcrack pressure of the spring-operated relief valve based on the measuredforce.

In some embodiments, a method for setting a set pressure or crackpressure for a spring-operated relief valve can include determining atotal relieved capacity for a relief event that includes one or morevalve lifts. The one or more valve lifts can be characterized based on aload cell measuring one or more corresponding forces applied by a mainspring during a relief event.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and form a part ofthis specification, illustrate embodiments of the invention and,together with the description, serve to explain the principles ofembodiments of the invention:

FIG. 1 is a cross-sectional view of a spring-operated pressure reliefvalve, including a load cell retained between a bonnet and a cap,according to an embodiment of the invention.

FIG. 2 is a cross-sectional view of a spring-operated pressure reliefvalve, including a load cell positioned between a pressure adjustmentmember and a spring washer, according to another embodiment of theinvention.

FIG. 3 is a cross-sectional view of a spring-operated pressure reliefvalve, including a load cell secured outside a valve housing, accordingto yet another embodiment of the invention.

FIG. 4 is a schematic diagram of a method of installing or calibrating aspring-operated relief valve, according to an embodiment of theinvention.

DETAILED DESCRIPTION

The following discussion is presented to enable a person skilled in theart to make and use embodiments of the invention. Various modificationsto the illustrated embodiments will be readily apparent to those skilledin the art, and the generic principles herein can be applied to otherembodiments and applications without departing from embodiments of theinvention. Thus, embodiments of the invention are not intended to belimited to embodiments shown, but are to be accorded the widest scopeconsistent with the principles and features disclosed herein. Thefollowing detailed description is to be read with reference to thefigures, in which like elements in different figures have like referencenumerals. The figures, which are not necessarily to scale, depictselected embodiments and are not intended to limit the scope ofembodiments of the invention. Skilled artisans will recognize theexamples provided herein have many useful alternatives and fall withinthe scope of embodiments of the invention.

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the attached drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways. Also, it is to be understood thatthe phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. For example, the useof “including,” “comprising,” or “having” and variations thereof hereinis meant to encompass the items listed thereafter and equivalentsthereof as well as additional items.

As used herein, unless otherwise specified or limited, the terms“mounted,” “connected,” “supported,” “secured,” and “coupled” andvariations thereof, as used with reference to physical connections, areused broadly and encompass both direct and indirect mountings,connections, supports, and couplings. Further, unless otherwisespecified or limited, “connected,” “attached,” or “coupled” are notrestricted to physical or mechanical connections, attachments orcouplings.

As briefly discussed above, certain systems and vessels require pressureprotection to avoid over-pressurization. Spring-operated pressure reliefvalves can be used in such systems to relieve and divert excess fluidpressure. In general, spring-operated pressure relief valves include aspring that is compressed by a predetermined value. The spring providesa force on a valve disc in a valve-closing direction (e.g., downward),thereby biasing the valve toward a closed position. The compression ofthe spring can be adjusted via a spring adjustment mechanism, such as anadjustable screw that controls the degree of compression of the springfor a given valve lift. When an opening (e.g., upward) force exerted bya pressurized fluid acting on the valve disc equals the closing (e.g.,downward) force of the spring, plus any ancillary forces (e.g., due tothe weight of a disc assembly), the valve begins to open. As the fluidpressure continues to increase, the spring is further compressed, andthe valve is further opened.

Spring-operated pressure relief valves are generally configured toprovide a set pressure, which is typically predetermined and presetbefore installation of the valves. The set pressure is typically apressure at which the valve opens and there is a significant relief ofsystem pressure, although other definitions are applied in differentinstallations, as is known in the industry. In some instances, the setpressure may be defined as the pressure at which a first audibleresponse (i.e., “pop”) can be heard by a user, as a spring-operatedpressure relief valve releases system pressure, or may be defined as thepressure at which leakage through a valve is first audible for humanoperators. As appropriate, the set pressure for a particular valve canbe adjusted by varying the compression of a spring within the valve,including by adjusting a pressure adjustment screw to compress orrelease a spring by a certain amount.

In addition to a set pressure, spring-operated pressure relief valvesfurther define a crack pressure. The crack pressure is a pressure atwhich the disc assembly of the valve first begins to lift from the valveseat in response to system pressure. In other words, the crack pressuremay be defined as a pressure at which the force of the fluid on a lineside of the valve seat equals the force exerted by the spring (and anyancillary forces) on a relief side of the valve seat. The effect of asystem reaching crack pressure can be minute fluid leakage or a lowdecibel audible noise (e.g., such as may not necessarily be audible tohuman operators). In some cases, when a spring-operated pressure reliefvalve is at crack pressure, the valve disc may lift from the valve seat.However, due to the relatively small distances of travel, conventionallift measurement devices are often unable to detect such a movementuntil after greater pressure has been applied. In some systems, the setpressure value can be a small percentage (e.g., 3-5%) larger than acrack pressure value, such that a set pressure can be defined relativeto a crack pressure (or vice versa), although other approaches arepossible.

In general, valve lift can be defined as a distance between seatingsurfaces of a disc assembly (e.g., a disc insert thereof) and a nozzlein a spring-operated pressure relief valve, as the valve transitionsbetween a closed and open position. The lift is said to be zero when thevalve is in a closed position, and the lift reaches a maximum when thevalve is in a fully opened position.

While the valve lift at crack pressure or at pressures only slightlyabove crack pressure is often undetectable using conventional liftmeasurement devices, some conventional systems can be used to help todetermine or adjust set pressure or otherwise measure valve lift athigher pressures. For example, some conventional systems include forcesensors to measure the total force required to move the internal movingparts of the valve, including a disc insert, a disc holder, a stem,etc., in combination with pressure sensors, position sensors, movablediaphragms or air bellows to define air-tight chambers, controllers thatcan control air pressure within those chambers (see, e.g., U.S. Pat.Nos. 4,761,999 and 4,349,885, both of which are incorporated herein byreference), and other components. Such systems can require complexarrangements and control, and precise positioning of sensors toaccurately measure force. Other conventional systems for determining andadjusting a set pressure include the use of a position transmitter andmagnets that require attachment to moving parts. Such arrangements canbe complicated and expensive to produce due to the involvement ofmultiple components encased in the position transmitter itself. Asanother example, some conventional approaches determine set pressurebased on identification of auditory signals (e.g., a first “pop”) by ahuman operator, as the compression of a spring for a valve is manuallyadjusted.

Embodiments of the disclosed invention can improve on these approachesand others, including by utilizing load measuring devices to determineloading of a biasing spring of a spring-operated pressure relief valveand to thereby determine valve lift, total relieved capacity for arelief event, and other related factors. For example, a force transducercan be used to determine valve lift of a spring-operated pressure reliefvalve by measuring the force exerted by (and on) the main spring of thevalve at any given time. Based on this measurement, the distance bywhich the spring has been compressed can then be readily calculated. Forexample, Hooke's law states that the force (F) needed to extend orcompress a spring by some distance (x) scales linearly with respect tothat distance by the factor of a spring rate (k): i.e., F=k·x. Thus, ifa spring rate for a given spring is known, along with the force appliedby (or to) the spring, the distance by which the system has beencompressed or extended can be readily determined.

In this regard, a spring rate is generally a characteristic of a givenspring, and can be readily determined in a variety of known ways.Further, a spring rate is generally constant, particularly outside ofextreme ends of the possible range of extension or compression of agiven spring. However, in some cases, a spring rate can be non-constant,varying based on temperature or other factors, particularly forrelatively large temperature changes.

In some embodiments of the disclosed invention, a load measuring deviceis attached or integrated into a spring-operated pressure relief valvethat includes a main spring to bias a disc assembly of the valve towarda valve seat on a nozzle of the valve (i.e., to bias the valve closed).The load measuring device can be configured as a load cell of a varietyof known types (or in other ways), and can be configured to measure theload exerted by the main spring on the disc assembly. The degree ofcompression of the main spring and, thereby, the lift of the valve maythen be determined based on the measured load, in combination with otherknown parameters of the spring-operated pressure relief valve, asappropriate, including the spring rate of the main spring, the area ofthe disc assembly that is exposed to line pressure, or the weight ofrelevant moving parts (e.g., of a valve spindle and the disc assembly).Correspondingly, whether a system is currently at (or above) a setpressure or a crack pressure can also be determined, even when suchsystem pressures may result in relatively small valve lift. Further,such an arrangement can allow continuous monitoring over time of thestate of the valve (e.g., open, closed, or at an intermediate position)and of actual valve lift, which can in turn be used to determine otherfactors, including estimates of the total fluid that has been relievedby the spring-operated pressure relief valve.

In some embodiments, a load measuring device that is configured todetermine force on a spring of a spring-operated relief valve can allowfor an automated or semi-automated setting of the set pressure of thespring-operated relief valve. For example, before installation in anindustrial setting, a valve inlet of a spring-operated relief valve maybe pressurized to a desired set pressure (or other pressure value). Apressure adjustment screw may then be used to adjust the compression ofa main spring of the valve, with the load cell measuring a currentspring force of the main spring for any given orientation of theadjustment screw (e.g., measuring such force continually at a particularsample rate). As generally discussed above, this spring force can thenbe converted (e.g., by a local or remote processor device) into adisplacement value for the main spring and, correspondingly, into avalve lift value for the valve.

Accordingly, by measuring the current spring force, a current valve liftcan be determined that corresponds to the current valve inlet pressureand the current orientation of the pressure adjustment screw. Further,an orientation of the pressure adjustment screw associated with adesired lift of the valve, for a given valve inlet pressure, can also besimilarly determined based on measurements by the load cell. This, inturn, can allow the valve to be configured to provide the desired setpressure during operation without necessarily relying on detection ofauditory signals (e.g., a first “pop”) and without requiring morecomplex (e.g., diaphragm-based) measurement systems.

In some embodiments, a load cell can transmit the measured load to aseparate controller as an electronic signal, such as may allow furtherprocessing at or remotely from a relevant valve assembly. In someembodiments, the electronic signal may be received by a device with adigital display, such as, for example, a computer monitor, such as mayallow display of alerts, alarms, or other information.

In some embodiments, it may be useful to arrange a load cell to be in afixed spatial relationship relative to a body of a spring-operatedpressure relief valve during operation of the valve. For example, a loadcell can be configured to be adjustably positioned before operation of aspring-operated pressure relief valve, relative to a valve body, bonnet,and cap of the valve, but can then be fixed against movement relative tothe valve body, bonnet, and cap during operation of the valve. In thisway, for example, a load from a main spring of the spring-operatedpressure relief valve can be measured without necessarily requiringcomplex structural arrangements such as additional springs, diaphragms,linkage, and so on.

For similar reasons, it may also be useful to arrange a load cell tomeasure a force exerted by a main spring of a spring-operated pressurerelief valve directly (i.e., via contact with the main spring) or via arigid intervening component. For example, a load cell can be configuredto measure a force exerted by a main spring via a rigid interveningcomponent that is urged toward the load cell by the main spring (e.g., aspring washer or rigid adjustment screw), so that complex interveningstructures or supporting measurements (e.g., of system pressure) are notnecessarily required as part of determining the force applied by themain spring (or determining a valve lift) based on a force measured bythe load cell. In this regard, for example, a load cell in someconfigurations may not measure aspects of operation of a main spring byway of forces applied to the load cell via a spindle of the relevantvalve. Similarly, as another example, a load cell in some configurationsmay be arranged to provide a mechanical connection between a main springand a body of a spring-operated relief valve, such that the main springpresses against the body, via the load cell, in order to apply springforce against the disc assembly of the valve.

Referring now to FIG. 1 , a spring-operated pressure relief valve 100according to one embodiment of the invention is shown. In theillustrated embodiment, the spring-operated relief valve 100 includes avalve body 102 and a single load cell 104. The relief valve 100 furtherincludes a pressure adjustment member configured as a pressureadjustment screw 108 that is engaged with a main spring 112. The mainspring 112 is configured to bias a disc assembly 116 towards a valveseat 120 at an inlet nozzle 124. The main spring 112 biases the discassembly 116 toward the valve seat 120 to define a set pressure of thespring-operated relief valve 100. A spindle 126 extends from the discassembly 116 to guide movement of the disc assembly 116 relative to thevalve seat 120. The relief valve 100 further includes a bonnet 128 thatacts as a cover to the valve body 102 and a cap 132 that covers thepressure adjustment screw 108 at one end of the bonnet 128. In general,the bonnet 128 and the cap 132 form a valve housing 134 of the valve100.

As shown in FIG. 1 , the load cell 104 is secured to the relief valve100 in order to measure the axial force applied to the pressureadjustment screw 108 by the main spring 112 (via an intervening upperspring washer 136). In the embodiment shown, in particular, the loadcell 104 includes internal threads that are dimensioned to receive andthreadably engage the pressure adjustment screw 108 so that the pressureadjustment screw 108 can be adjusted relative to the load cell 104 andthe housing 134 to adjust a degree of compression of the main spring112.

With continued reference to FIG. 1 , in the illustrated embodiment, theload cell 104 is retained between the bonnet 128 and the cap 132 so thatthe load cell 104 is immovable (i.e., has an unchanging fixed spatialrelationship) relative to the housing 134, and the spindle 126 ismovable relative to the load cell 104. In particular, in the illustratedembodiment, the spindle 126 is configured to move through the load cell104 to open and close the spring-operated relief valve 100. Further, thepressure adjustment screw 108 (i.e., as a rigid body) is configured totransmit axial forces from the main spring 112 (and the spring washer136), to the bonnet 128 and cap 132, only via the load cell 104. Thus,in the illustrated embodiment and as further discussed below, the loadcell 104 is arranged to directly measure, via an equal and oppositereaction force, effectively the entirety of the force exerted by themain spring 112 on the disc assembly 116 (minus incidental frictionallosses from the various moving components). In other embodiments,however, including as discussed below, a load cell can be otherwisedisposed, including with one or more additional (or alternative)intervening rigid components. Further, any variety of types of loadcells can be used, depending on the particular context and desiredsensing range.

In use, the main spring 112 applies equal and opposite forces to upperand lower spring washers 136, 138 to bias the disc assembly 116,relative to the bonnet 128, toward the closed orientation (as shown). Ingeneral, the upper spring washer 136 is disposed opposite the mainspring 112 from the disc assembly 116 and the lower spring washer 138 isdisposed opposite the main spring 112 from the upper spring washer 136.Each of the upper and lower spring washers 136, 138 generally provides aspring seat which the main spring 112 can bear against.

Because the load cell 104 secures the upper spring washer 136 relativeto the bonnet 128, via the intervening pressure adjustment screw 108,the force from the main spring 112 at the upper spring washer 136 can bedetermined by the load cell 104. Namely, the load cell 104 is inmechanical communication with the main spring 112 so that the load cell104 can measure a force exerted by the main spring 112 on the discassembly 116 as the disc assembly 116 and the spindle 126 move relativeto the valve seat 120 and the load cell 104 (e.g., to open the valve 100relative to flow across the valve seat 120). Correspondingly, in theillustrated embodiment, the load cell 104 is not in mechanicalcommunication with the disc assembly 116 via the spindle 126 to measurethe force exerted by the main spring 112. Thus, as generally discussedabove, the degree of compression of the main spring 112 can be readilydetermined based on force measurements at the load cell 104, as can,correspondingly, the displacement of the disc assembly 116 relative to areference position (e.g., fully closed) without reference to a measuredpressure of the fluid.

During setup operations (e.g., an initial configuration) for the reliefvalve 100 of FIG. 1 , as the pressure adjustment screw 108 is adjustedin opposing directions, the compression of the main spring 112 increasesor decreases, respectively, which correspondingly increases or decreasesthe crack pressure and the set pressure of the relief valve 100. For adesired set (or crack) pressure and valve size, the required load valueon the main spring 112 can be computed and the pressure adjustment screw108 can then be adjusted until this load—and the desired set (or crack)pressure—is achieved, as indicated by the load cell 104. Or, as alsodiscussed above, the inlet 124 of the relief valve 100 can bepressurized at a desired set (or other) pressure, and the measurementsby the load cell 104 can be used, in combination with other knownfactors for the valve 100, to identify valve lift and thereby determinea particular setting of the pressure adjustment screw 108 at which anappropriate opening of the valve 100 results (e.g., as corresponds tocrack pressure or set pressure). For example, the mathematical productof the applied pressure and a relevant area of the disc assembly 116 canindicate an opening force on the disc assembly 116 by the appliedpressure. Under known principles, and in combination with the change inload measured by the load cell due to application of the appliedpressure, that force can then be used to derive the distance by whichthe disc assembly 116 has lifted (i.e., the valve lift).

Similarly, during operation, when the disc assembly 116 is lifted fromthe valve seat 120 by system pressure, the valve lift (L) can becalculated as a function of a current load cell reading (LC_(c)), aninitial load cell reading (LC₀), and the spring rate (k) (e.g., asL=((LC_(c)−LC₀)/k). In some cases, the occurrence and extent of a relief(or other) event can then be determined accordingly.

In different embodiments, load cells can be arranged in a variety ofways in order to appropriately measure the force on a main spring of avalve, including as may embody similar principles as discussed relativeto FIG. 1 , above. In this regard, for example, FIG. 2 illustrates aspring-operated relief valve 200 that includes a valve body 202 andvarious other similar components to the valve 100 (which operatesimilarly). In the embodiment illustrated in FIG. 2 , a load cell 204 isdisposed between an upper spring 236 washer and a pressure adjustmentscrew 208. Similar to the load cell 104 shown in FIG. 1 , the load cell204 as shown in FIG. 2 can measure the force exerted by a main spring212 against the upper spring washer 236, as corresponds to the forceexerted by the main spring 212 to bias a disc assembly 216 toward avalve seat 220. Thus, as similarly described above, measurements fromthe load cell 204 can be used to identify crack or set pressures, toquantify flow for relief events, or to otherwise monitor the valve 200.

Generally similarly to the load cell 104, during operation of the valveto sense and relieve pressure, the load cell 204 is immovably secured tothe valve 100 relative to a valve housing 234. In particular, the loadcell 204 is secured within the valve housing 234 and is in mechanicalcommunication with the main spring 212 via the upper spring washer 236.Further, in the illustrated embodiment, the pressure adjustment screw208 is in threaded engagement with a bonnet 228 of the housing 234, andreceives a spindle 226 that extends from the disc assembly 216. Thespindle 226 can also extend through the load cell 204 to be moveablethrough the load cell 204 to open and close the spring-operated reliefvalve 200 (i.e., the spindle 226 is not in mechanical communication withthe load cell 204 so as to transmit force from the main spring 212 tothe load cell 204).

With the illustrated arrangement, therefore, like the valve 100, thepressure adjustment screw 208 of the valve 200 can be adjusted to setthe set pressure or crack pressure of the valve 200. However,differently from the valve 100, as the pressure adjustment screw 208 ismoved relative to the housing 234, the load cell 204 can also be movedrelative to the housing 234 to set the set pressure (i.e., adjust thedegree of compression of the main spring 212). Thus, the load cell 204is not absolutely immovable relative to the housing 234. However,because the pressure adjustment screw 208 is generally fixed againstmovement during operation of the valve 200 to sense and relieve systempressure, and the load cell 204 is mechanically secured relative to thehousing 234 by the adjustment screw 208, the load cell 204 willgenerally be immovable relative to the housing 234 during operation ofthe valve 200 (as also noted above).

In some embodiments, a load cell can be integrated into other componentsof a spring-operated relief valve. For example, in a configurationsimilar to that shown in FIG. 2 , a load cell may be integrated with aspring washer for a main spring of a spring-operated relief valve. Ingeneral, a load cell may be disposed at any location where the axialspring load can be measured, including on or in an upper or lower springwasher, or at any variety of locations that are appropriately connectedto a main spring such that the spring force on the disc assembly may bemeasured.

For example, in some embodiments, a load cell can be disposed between alower spring washer and a disc assembly of a spring-operated reliefvalve. As described above, upper and lower spring washers providerespective spring seats against which the main spring can bear against.As a result, the main spring applies equal and opposite forces on eachof the spring washers. Therefore, in an embodiment where the load cellis disposed between the lower spring washer and the disc assembly, theload cell can directly measure a force exerted on the main spring of therelief valve, similar to the embodiments described with reference toFIGS. 1 and 2 . However, configurations in which a load cell isimmovably fixed relative to a housing to directly measure a forceapplied by a main spring may be particularly beneficial, including forreasons discussed above.

In another embodiment, as shown in FIG. 3 , a valve 300 can include avalve body 302 and a valve housing 334. In the illustratedconfiguration, the valve 300 also includes a load cell 304 that isimmovably fixed relative to the valve housing 334, to the outside of abonnet 328 (and the housing 334 in general). Similar to the embodimentillustrated in FIG. 1 , the load cell 304 in the embodiment of FIG. 3includes a threaded hole extending therethrough that is dimensioned toreceive a threaded pressure adjustment screw 308. The threaded pressureadjustment screw 308 engages a rigid unthreaded pressure adjustment tube340, which is configured to compress a main spring 312 of the valve 300by adjustable amounts, corresponding to different positions of theadjustment screw 308.

Like the valves 100, 200, the valve 300 includes a spindle 326 thatextends from a disc assembly 316 to guide movement of the disc assembly316 relative to a valve seat 320. The spindle 326 extends into pressureadjustment tube 340 while remaining mechanically untied from the loadcell 304 (e.g., similarly to the spindles 126, 226 relative to the loadcells 104, 204). Thus, in the illustrated embodiment, the load cell 304is mechanically coupled to the main spring 312, for direct measurementof the force applied by the main spring 312, via the pressure adjustmenttube 340 that extends between the load cell 304 and an upper springwasher 336. However, other arrangements are possible in otherembodiments, including with additional (or alternative) rigidintervening components.

Thus, the load cell 304 can measure the axial load imparted on thepressure adjustment screw 308 by the main spring 312, as transmitted viathe upper spring washer 336 and the pressure adjustment tube 340. Inparticular, as may help to allow the illustrated simplicity of thearrangement and associated monitoring of the valve 300, the load cell304 is not in mechanical communication with the main spring 312 via thedisc assembly 316 of the valve 300 or the spindle 326, to measure forceon the main spring 312. Relatedly, the force measured by the load cell304 directly corresponds to a force of fluid on the disc assembly 316(or, more generally, to the force applied by the main spring 312 to thedisc assembly 316, including when the system is below set or crackpressure), without necessarily requiring the sensing of other referencepressures or forces (e.g., a measured pressure of the fluid). Similar tothe arrangements illustrated in FIGS. 1 and 2 , measurements by the loadcell 304 can be used in order to determine an appropriate setting of thepressure adjustment tube 340, such as to initially configure the valve300 for a particular set or crack pressure, and can be used to monitorlift of the valve during operation, including at crack pressure (andotherwise).

In some implementations, devices or systems disclosed herein can beutilized, manufactured, or installed using methods embodying aspects ofthe invention. Correspondingly, any description herein of particularfeatures, capabilities, or intended purposes of a device or system isgenerally intended to include disclosure of a method of using suchdevices for the intended purposes, of a method of otherwise implementingsuch capabilities, of a method of manufacturing relevant components ofsuch a device or system (or the device or system as a whole), and of amethod of installing disclosed (or otherwise known) components tosupport such purposes or capabilities. Similarly, unless otherwiseindicated or limited, discussion herein of any method of manufacturingor using for a particular device or system, including installing thedevice or system, is intended to inherently include disclosure, asembodiments of the invention, of the utilized features and implementedcapabilities of such device or system.

In this regard, for example, FIG. 4 illustrates an example method thatcan be implemented relative to various spring-operated relief valvesdisclosed herein, and associated control systems. In the discussionbelow, reference may be made in particular to only a select one or moreof the spring-operated relief valves 100, 200, 300. However, the methodsdisclosed herein can generally be implemented relative to any of these(or other) valves according to the disclosure.

In particular, FIG. 4 illustrates a method 400 that includes using 410 aload cell (e.g., the load cell 104) to directly measure a force appliedby a main spring of a spring-operated relief valve (e.g., the mainspring 112). Based on data from the load cell measurement, the method400 can further include conducting 420 one or more of various additionalcalibrating, monitoring, or other operations. For example, the method400 can include determining 422 a valve lift for the spring-operatedrelief valve based on the measured force or monitoring 424 a current setpressure or crack pressure of the spring-operated relief valve based onthe measured force. In this regard, for example, a valve lift can bedetermined 422 or a crack or set pressure can be monitored 424 invarious ways, including as discussed above: e.g., determining valve liftbased on measured force and a spring constant of the corresponding mainspring, or determining a current set pressure based on equating pressureforce on a disc assembly (e.g., the disc assembly 116) with spring forceas measured by a load cell. In particular, in some cases, a change inload sensed by a load cell that directly measures a force applied by themain spring of a relief valve can indicate movement of a disc assemblyfrom a valve seat because the force acting on the main spring generallyremains stagnant until a set pressure is reached.

In some implementations, the conducted 420 operations can includesetting 426 a desired set pressure or crack pressure of thespring-operated relief valve. For example, a target load on a mainspring of the spring-operated relief valve can be determined, as maycorresponding to the desired set pressure or crack pressure. Then, abias of a main spring (e.g., the main spring 112) can be adjusted untilthe force measured by the load cell corresponds to the target load.

In some implementations, the conducted 420 operations can includedetermining 428 a total relieved capacity for a relief event based on aplurality of valve lifts that are identified based on the load cellmeasuring a plurality of forces applied by the main spring during therelief event. For example, a numerical integration of valve lifts andflow rates that correspond to the valve lifts can be completed for arelief event, with the resulting sum of flow over time providing anindication of the total relieved capacity for the relief event.

In some implementations, the conducted 420 operations can includecalibrating 430 a spring-operated pressure relief valve. For example,calibrating 430 a spring-operated relief valve can include pressurizinga valve inlet (e.g., the inlet nozzle 124) of the spring-operated reliefvalve. The compression of a main spring (e.g., the main spring 112) ofthe spring-operated relief valve can then be adjusted among one or morecompression loads (e.g., sequentially over a predetermined range) andthe load cell can be used to measure the compression load of the mainspring at one or more of the adjustments of the compression of the mainspring. Based on the load cell measurements, a current set pressure orcrack pressure can then be identified. For example, a current set orcrack pressure can be identified directly from a pressure reading at thevalve inlet upon the load cell measurement indicating appropriate valvelift. As another example, a current set or crack pressure can beidentified indirectly by solving a force balance equation between theforce measured by a load cell and the pressure force applied to therelevant disc assembly when the load cell indicates the appropriatevalve lift.

Thus, embodiments of the disclosed invention can provide an improvementover conventional arrangements for setting a set pressure of aspring-operated relief valve, detecting crack or set pressure of thevalve, or otherwise monitoring the valve during operation. The previousdescription of the disclosed embodiments is provided to enable anyperson skilled in the art to make or use the invention. Variousmodifications to these embodiments will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other embodiments without departing from the spirit or scopeof the invention. Thus, the invention is not intended to be limited tothe embodiments shown herein but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

In some embodiments, aspects of the invention, including computerizedimplementations of methods according to the invention, can beimplemented as a system, method, apparatus, or article of manufactureusing standard programming or engineering techniques to producesoftware, firmware, hardware, or any combination thereof to control aprocessor device (e.g., a serial or parallel general purpose orspecialized processor chip, a single- or multi-core chip, amicroprocessor, a field programmable gate array, any variety ofcombinations of a control unit, arithmetic logic unit, and processorregister, and so on), a computer (e.g., a processor device operativelycoupled to a memory), or another electronically operated controller toimplement aspects detailed herein. Accordingly, for example, embodimentsof the invention can be implemented as a set of instructions, tangiblyembodied on a non-transitory computer-readable media, such that aprocessor device can implement the instructions based upon reading theinstructions from the computer-readable media. Some embodiments of theinvention can include (or utilize) a control device such as anautomation device, a special purpose or general purpose computerincluding various computer hardware, software, firmware, and so on,consistent with the discussion below. As specific examples, a controldevice can include a processor, a microcontroller, a field-programmablegate array, a programmable logic controller, logic gates etc., and othertypical components that are known in the art for implementation ofappropriate functionality (e.g., memory, communication systems, powersources, user interfaces and other inputs, etc.).

The term “article of manufacture” as used herein is intended toencompass a computer program accessible from any computer-readabledevice, carrier (e.g., non-transitory signals), or media (e.g.,non-transitory media). For example, computer-readable media can includebut are not limited to magnetic storage devices (e.g., hard disk, floppydisk, magnetic strips, and so on), optical disks (e.g., compact disk(CD), digital versatile disk (DVD), and so on), smart cards, and flashmemory devices (e.g., card, stick, and so on). Additionally it should beappreciated that a carrier wave can be employed to carrycomputer-readable electronic data such as those used in transmitting andreceiving electronic mail or in accessing a network such as the Internetor a local area network (LAN). Those skilled in the art will recognizethat many modifications may be made to these configurations withoutdeparting from the scope or spirit of the claimed subject matter.

Certain operations of methods according to the invention, or of systemsexecuting those methods, may be represented schematically in the FIGS.or otherwise discussed herein. Unless otherwise specified or limited,representation in the FIGS. of particular operations in particularspatial order may not necessarily require those operations to beexecuted in a particular sequence corresponding to the particularspatial order. Correspondingly, certain operations represented in theFIGS., or otherwise disclosed herein, can be executed in differentorders than are expressly illustrated or described, as appropriate forparticular embodiments of the invention. Further, in some embodiments,certain operations can be executed in parallel, including by dedicatedparallel processing devices, or separate computing devices configured tointeroperate as part of a large system.

As used herein in the context of computer implementation, unlessotherwise specified or limited, the terms “component,” “system,”“module,” and the like are intended to encompass part or all ofcomputer-related systems that include hardware, software, a combinationof hardware and software, or software in execution. For example, acomponent may be, but is not limited to being, a processor device, aprocess being executed (or executable) by a processor device, an object,an executable, a thread of execution, a computer program, or a computer.By way of illustration, both an application running on a computer andthe computer can be a component. One or more components (or system,module, and so on) may reside within a process or thread of execution,may be localized on one computer, may be distributed between two or morecomputers or other processor devices, or may be included within anothercomponent (or system, module, and so on).

The invention claimed is:
 1. A spring-operated relief valve comprising:a valve housing a valve seat; a disc assembly configured to seal againstthe valve seat to close the spring-operated relief valve; a main springarranged to bias the disc assembly towards the valve seat to define aset pressure of the spring-operated relief valve; a load cell that,during operation of the spring-operated relief valve, is in a fixedspatial relationship relative the valve housing and in mechanicalcommunication with the main spring, the load cell being therebyconfigured to measure a force exerted by the main spring on the discassembly as the disc assembly moves relative to the valve seat; and apressure adjustment member, wherein the load cell includes internalthreads and the pressure adjustment member is threadably received by theinternal threads, the pressure adjustment member being therebythreadably adjustable, relative to the load cell and the valve housing,to adjust a degree of compression of the main spring.
 2. Thespring-operated relief valve of claim 1, further comprising: a spindlethat extends from the disc assembly to guide movement of the discassembly relative to the valve seat; wherein, during operation of thespring-operated relief valve, the spindle is movable relative to theload cell to open and close the spring-operated relief valve relative tofluid flow across the valve seat.
 3. The spring-operated relief valve ofclaim 2, wherein the spindle extends through the load cell, to bemovable through the load cell to open and close the spring-operatedrelief valve relative to fluid flow across the valve seat.
 4. Thespring-operated relief valve of claim 1, wherein the load cell is inmechanical communication with the main spring via the pressureadjustment member to measure the force exerted by the main spring on thedisc assembly.
 5. The spring-operated relief valve of claim 4, whereinthe valve housing includes a bonnet and a cap; and wherein the load cellis retained between the bonnet and the cap.
 6. The spring-operatedrelief valve of claim 1 further comprising: a first spring washerdisposed opposite the main spring from the disc assembly; and a secondspring washer disposed opposite the main spring from the first springwasher, between the main spring and the disc assembly; and wherein theload cell is in mechanical communication with the main spring via thefirst spring washer.
 7. The spring-operated relief valve of claim 6,wherein the load cell is retained between the first spring washer and apressure adjustment member that is threadably adjustable relative to thevalve housing to adjust a degree of compression of the main spring. 8.The spring-operated relief valve of claim 6, wherein the load cell isintegrated with the first spring washer.
 9. The spring-operated reliefvalve of claim 1, wherein the force measured by the load cell directlycorresponds to a force of fluid on the disc assembly, without referenceto a measured pressure of fluid at an inlet of the spring-operatedrelief valve.
 10. The spring-operated relief valve of claim 1, whereinthe load cell is positioned exterior to the valve housing.
 11. Thespring-operated relief valve of claim 10, further comprising: a spindlethat extends from the disc assembly to guide movement of the discassembly relative to the valve seat; and a pressure adjustment tube thatreceives the spindle and extends between a spring washer and the loadcell to transmit force from the main spring to the load cell.
 12. Thespring-operated relief valve of claim 11, further comprising: a pressureadjustment member that is threadably adjustable relative to the loadcell to adjust, via the pressure adjustment tube, a degree ofcompression of the main spring.
 13. The spring-operated relief valve ofclaim 12, wherein the pressure adjustment member is adjustable fromoutside of the valve housing.
 14. A spring-operated relief valvecomprising: a valve housing; a valve seat; a disc assembly configured toseal against the valve seat to close the spring-operated relief valve; aspindle that extends from the disc assembly to guide movement of thedisc assembly relative to the valve seat; a main spring arranged to biasthe disc assembly towards the valve seat to define a set pressure of thespring-operated relief valve; and a load cell that, during operation ofthe spring-operated relief valve, is one of immovably secured within thevalve housing or immovably secured outside the valve housing; whereinthe load cell is in mechanical communication with the main springdirectly or via a rigid intervening component, the load cell beingthereby configured to measure a force exerted by the main spring on thedisc assembly as the disc assembly and the spindle move relative to thevalve seat and the load cell, and wherein, during operation of thespring-operated relief valve, the spindle is movable relative to theload cell to open and close the spring-operated relief valve relative tofluid flow across the valve seat and the load cell is not in mechanicalcommunication with the disc assembly via the spindle to measure theforce exerted by the main spring.
 15. A method of installing orcalibrating a spring-operated relief valve, the method comprising: usinga load cell to directly measure a force applied by a main spring of thespring-operated relief valve, the main spring being arranged to bias adisc assembly of the spring-operated relief valve towards a valve seatof the spring-operated relief valve to define a set pressure and a crackpressure of the spring-operated relief valve; pressurizing a valve inletof the spring-operated relief valve; adjusting the compression of themain spring among a plurality of compression loads; using the load cellto measure the compression load of the main spring at a selectadjustment of the compression of the main spring; identifying avalve-opening movement of the spring-operated relief valve thatcorresponds to the select adjustment of the compression of the mainspring; and upon identifying the valve-opening movement, determining acurrent set pressure or crack pressure based on the measured compressionload; and one or more of: determining a valve lift for thespring-operated relief valve based on the measured force; monitoring acurrent set pressure or crack pressure of the spring-operated reliefvalve based on the measured force; or setting a desired set pressure orcrack pressure of the spring-operated relief valve by: determining atarget load on a main spring of the spring-operated relief valve, thetarget load corresponding to the desired set pressure or crack pressure;and adjusting a bias of the main spring of the spring-operated reliefvalve until the force measured by the load cell corresponds to thetarget load.
 16. The method of claim 15, further comprising: determininga total relieved capacity for a relief event based on a plurality ofvalve lifts that are identified based on the load cell measuring aplurality of forces applied by the main spring during the relief event.17. The method of claim 15, wherein the load cell is fixedly securedrelative to a valve housing of the spring-operated relief valve at oneof: outside of the valve housing of the spring-operated relief valve;between a pressure adjustment member and an upper spring washer of thespring-operated relief valve; or between a bonnet and a cap of thespring-operated relief valve.